This lesson helps introduce students to the concept that temperature causes molecules and atoms to move faster and farther apart, which in turn causes the change from solid to liquid, and liquid to gas.

Cheese Tomography

A hot area in engineering is the idea of non-destructive evaluation—using sophisticated scanning techniques to examine an item without taking it apart or cutting it open. Now one researcher has adapted the technology for a rather tasty material.

Transcript

Making Swiss cheese is no trivial matter. The size, number, and distribution of the holes—or eyes—are all regulated by the government. Cheesemakers have to cut out samples and use statistics to determine whether a batch is developing properly—a time-consuming and wasteful process.

But a few years ago, Moshe Rosenberg, a dairy technology specialist at the University of California at Davis, had a brainstorm. He paid a visit to the local hospital.

Rosenberg: I just took wheels of Swiss cheese, and I asked a favor from my friends at one of the oncology departments to allow me to do what I would call cheese tomography. His friend took an MRI, or magnetic resonance image, of the cheese. It showed in 3D the pattern of eyes inside the wheel. Based on that success, Rosenberg and his colleagues have now adapted MRI technology just for cheese.

Rosenberg: So we envision an online system—the image will be compared online with the regulations, and then it will be Grade A, Grade B, Grade C without touching the cheese.

The researchers are now looking for partners who can make a prototype.

For the American Association for the Advancement of Science, I'm Bob Hirshon.

Making Sense of the Research

Evaluation of the holes or "eyes" found within Swiss cheese can reveal a great deal about the quality of the cheese, and the process used to make it. Currently, scientists must either cut or extract a plug from a wheel of cheese to determine whether the cheese is developing properly. Statistical sampling is then used to decide whether the whole lot, or batch, is viable—an important determination, since aging or ripening cheese is a lengthy and expensive process. It is in the best interest of manufacturers to know as soon as possible whether a lot will be successful.

Scientists look at the size, quantity, and distribution of the eyes, to make determinations about difficulties that occurred in processing, such as those related to the equipment or temperature gradient used. By looking for irregularities in the quantity and pattern of the eyes, scientists can also determine the presence of microorganisms in the cheese. While some of these microorganisms are introduced intentionally as part of the manufacturing process—such as the gas-producing ones responsible for the holes in Swiss cheese—undesirable microorganisms may also reside in the cheese. Previously, enumerating and identifying these undesirable microorganisms has required time-consuming and expensive analysis. That is, until now.

Now try to answer the following questions:

How are the eyes in Swiss cheese formed?

What do the eyes tell us about the cheese?

What factors are inspectors looking for when examining Swiss cheese? How is it graded?

Go to the How Stuff Works' article titled Cheese Making to learn more about cheesemaking and how Swiss cheese gets its holes. Or, see Science Daily'sResearchers Develop Tastier Low-Fat Cheddar to read about the role of bacteria in producing more palatable low-fat cheese. To read about other foods that are produced by microbes, go to Microbe Zoo's Snack Bar.

The Microbe Zoo offers an interesting look at the growing field of Microbial Ecology.